Solid state step attenuators are used to control the amplitude of high frequency electrical signals in a variety of microwave systems because of their high reliability and low cost. When incorporated into an instrument such as a signal source, a solid state step attenuator provides amplitude control at the signal source's output. The solid state step attenuator has a low attenuation state and a high attenuation state, enabled by control signals. In the low attenuation state, electrical signals applied to the attenuator propagate through the attenuator relatively unimpeded, while in the high attenuation state, electrical signals applied to the attenuator are reduced in amplitude by a preset attenuation value. Solid state step attenuators have low manufacturing cost because they are fabricated monolithically, tested in wafer form and packaged inexpensively.
Unfortunately, solid state switches and other circuit elements used in the solid state step attenuator have inherent parasitic impedances, causing a variation in the attenuator's frequency response. Compensation for the variation in the frequency response may be achieved external to the attenuator by adjusting the amplitude of the applied electrical signal according to the signal frequency. However, external frequency compensation increases the cost and complexity of the microwave system in which the solid state step attenuator is used.